Whether the ruling government will be weakened or strengthened by a wave election depends on how we look at it. Wave election is a political term used to describe an election outcome or cycle in which a political party enjoyed a landslide victory or a significant election gains in an election. The term is mostly used for the election of the US Senate or House of representatives.
What will make a wave election weakens the ruling government is when you have a situation where the opposition party to the ruling government pull more members. In this case, the opposition becomes the majority party in the house and this isn't good enough for the government because there won't a close relationship between the executive and the legislative arm of government.
But in a situation where the ruling party in the country pull more members than the opposition, you would see that, there would be a close relationship between the government and the legislatures, because most of the programs intended by the government would be easily actualized.